IMS: Add carrier config for RTT always enabled

Add carrier config for RTT always enabled

Change-Id: I06bae4747db38a0d0b6591337306206db53c3573
CRs-Fixed: 2430071
diff --git a/telephony/java/android/telephony/CarrierConfigManager.java b/telephony/java/android/telephony/CarrierConfigManager.java
index e0376ff..255653d 100755
--- a/telephony/java/android/telephony/CarrierConfigManager.java
+++ b/telephony/java/android/telephony/CarrierConfigManager.java
@@ -2216,6 +2216,12 @@
     public static final String KEY_RTT_DOWNGRADE_SUPPORTED_BOOL = "rtt_downgrade_supported_bool";
 
     /**
+     * Flag indicating whether RTT is always enabled.
+     * @hide
+     */
+    public static final String KEY_RTT_ALWAYS_ENABLED_BOOL = "rtt_always_enabled_bool";
+
+    /**
      * The flag to disable the popup dialog which warns the user of data charges.
      * @hide
      */
@@ -3076,6 +3082,7 @@
         sDefaults.putStringArray(KEY_ROAMING_OPERATOR_STRING_ARRAY, null);
         sDefaults.putBoolean(KEY_SHOW_IMS_REGISTRATION_STATUS_BOOL, false);
         sDefaults.putBoolean(KEY_RTT_SUPPORTED_BOOL, false);
+        sDefaults.putBoolean(KEY_RTT_ALWAYS_ENABLED_BOOL, false);
         sDefaults.putBoolean(KEY_TTY_SUPPORTED_BOOL, true);
         sDefaults.putBoolean(KEY_DISABLE_CHARGE_INDICATION_BOOL, false);
         sDefaults.putBoolean(KEY_SUPPORT_NO_REPLY_TIMER_FOR_CFNRY_BOOL, true);